Mandrel for opening a tube of flexible material

ABSTRACT

A mandrel for opening a tube of flexible banding material wherein the tube is delivered in flat ribbon-like form with creased side edges is disclosed. The mandrel is in the form of a tetrahedron with two sets of surfaces which are in the form of isosceles triangles with each set of faces inclining towards one another to form a common base. A pair of relatively yieldable, sharp-edged wedging elements are disposed on each common base. Biasing means bias the wedging elements outwardly to limit positions at the ends of the common bases. Use of the mandrel to open a tube of flexible, heat-shrinkable banding material and creasing the material at points displaced 90° from the initial creases is disclosed.

FIELD OF THE INVENTION

In its preferred application, this invention relates to the sealing ofcontainers such as glass bottles with a band of heat sealable plasticmaterial fed in the form of a flat web or tube and more particularly toan opening mandrel for opening the tube, wherein the tube is typicallyflexible, heat-shrinkable, plastic material.

BACKGROUND OF THE INVENTION

Briefly, the banding material used in the heat sealing of closures tocontainers is supplied in the form of a substantially continuous roll oftubular material with the walls of the tubular material flattened andfed off the roll as a semi-continuous ribbon having opposed creasededges. The ribbon of banding material is fed from the roll to equipmentwhich opens it and thereafter delivers the opened banding material to astation on a production line where pieces are cut to a suitable size andapplied over the lids of containers as they move past the station. Oncein place, an application of heat to the banding material causes it toshrink tightly over the lid, providing a protective seal which must bebroken in order to remove the lid from the container. As is wellrecognized, these seals provide a measure of protection to the ultimatepurchaser who can readily tell from the condition of the heat sealedband whether someone has opened the container between the time it issealed and the time of purchase.

The use of tetrahedrally-shaped mandrels having faces which areisosceles triangles to open the band of heat sealable material is knownin the art. The banding material is drawn over the mandrel with thecommon corners of two of the isosceles triangular faces being inalignment with and in contact with the inner surfaces of the opposedcreases of the material. As the banding material is drawn relativelylengthwise of the mandrel it is wedged open by these faces. The cornersformed at the common base of the other two triangular faces impartcreases which are offset by 90° with respect to the original creases.Opening mandrels which perform this function are known per se and aredisclosed in U.S. Pat. No. 4,148,171. The imparting of these additionalcreases acts to open the band and to naturally hold it in the openposition so that it can be quickly and reliably fitted over thecontainer lid during the application and sealing steps of the bandingprocess.

SUMMARY AND OBJECTS OF THE INVENTION

The invention described and claimed herein provides improvements in theprior art band opening mandrels which accommodate changes in thedimensions in the band of heat sealable material, and an object of theinvention is the provision of a mandrel having pairs of self-adjusting,wing-type corner members at the ends of the edges of each of the twosets of wedging surfaces.

A related object of the invention is the provision of a mandrel foropening a band of flat, tubular material such as a tubular band of heatsealing tape material which substantially reduces the incidence ofdamage to the material.

A still further object of the invention is the provision of a mandrelwhich more efficiently opens a flattened band of flexible material.

A still further object of the invention is the provision of a mandrelfor opening heat sealing tape or like banding material having improvedwear and durability characteristics.

The above and other objects of the invention are achieved by a mandrelwhich is tetrahedrally shaped having its four faces shaped asequal-sized isosceles triangles with the oppositely disposed facesterminating in common base portions and wherein each of said baseportions has a pair of relatively yieldable wedging corner elementsdisposed at each end thereof, with biasing means for urging said wedgingelements relatively outwardly to limit positions at the opposite ends ateach of said base portions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 show plan and elevational views respectively of apparatusincorporating the tetrahedrally-shaped wedging mandrels of the presentinvention;

FIG. 3 is a side elevational view, partly in section, of the apparatusshown in FIG. 2;

FIG. 4 is an exploded perspective view of a wedging mandrelincorporating the principles of the present invention;

FIG. 5 is a sectional view taken on line 5--5 of FIG. 4;

FIG. 6 is a top view of the wedging mandrel of FIG. 5; and

FIG. 7 is a diagrammatic view showing the application of cut pieces ofbanding material being applied over the closure cap for a container.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference first to FIGS. 1 through 3, and as perhaps is best shownin FIG. 2, the heat sealable tubular banding material in ribbon ortape-like form is shown at 10 as being advanced through a pair of guiderolls 11 from a supply reel not shown. With reference to these drawingsit should be understood that the banding material, which is a readilyavailable commercial item, is exaggerated in thickness in the drawings.Banding material of the type used in the invention commonly has a wallthickness of a few thousandths of an inch, although thicker material issometimes employed as will readily be appreciated by those skilled inthe art. As delivered from the reel, the banding material is alreadyprovided with sharply creased opposed edges 12 and 13, as can be seen inFIG. 1 where the material is partially shown in section.

In accordance with known procedure, a wedge-shaped mandrel is initiallyfitted within the tube of material, the tape being broken away in FIGS.2 and 3 to illustrate the position of the wedge and the way in which themandrel affects the opening. Briefly stated the mandrel 9 is preferablyprovided with four isosceles triangular faces so as to form two wedgeswhich are offset from one another by 90°. The tubular mandrel is drawndownwardly relatively to the mandrel and between the surfaces of a pairof spaced apart mandrel support shafts 14 and 15. A pair of retainingcollars 16, secured to shaft 15 by means of set screws 17, preventmovement of the mandrel in directions axially of shafts 14 and 15.

With reference now to FIGS. 4 through 6, the generallytriangularly-shaped faces are identified by the numerals 18a, b, c, andd, with each face forming an isosceles triangle. Faces 18c and bterminate in an elongated common wedging base portion 19, whereas faces18a and d terminate in a common base portion 20.

In accordance with the invention, yieldable wedging means are providedat the ends of the common base portions to accommodate differences inthe tape size which may arise because of changes in humidity ortemperature, or changes occurring because of manufacturing tolerances.Still further the yieldable wedging means allows for occasionalmisalignment of the tape feed parts relative to the mandrel. For thispurpose, base portion 19 is provided with a grooved slot whichpreferably is in the form of a key way 21. Base portion 20 is providedwith a similarly shaped key way or slot 22. Mounted in the slots 21 and22 for slidable movement therein are parts or wedging extensions 23having correspondingly shaped key shaped bases 23a which fit within theslots. Biasing means comprising a spring 24 urges each set of parts 23outwardly along the key ways to the outer limits of said base portions.Stop means which conveniently take the form if pins 26 pass through thekey ways and through slots 27 within the parts 23 so as to limitmovement of the parts. As best shown in FIG. 5 when the parts 23 are inthe limit positions to which they are urged by the biasing spring 24,their outer surfaces substantially act as extensions of the adjoiningopposed set of triangular faces and their side surfaces incline towardone another as extensions of the other set of triangular faces. Thus theparts 23 form laterally yieldable wedging extensions of the wedging baseportions 19 and 20.

Preferably parts 23 are further provided with lengthwise slots 30 whichreceive thin plates made of metal or like relatively stiff material, theplates 31 being held in place within the slots by such suitable means aspins 32. Preferably, the plates 31 each have an inclined edge portion 33which inclines inwardly from the ends of the wedging extensions 23.

As set forth above, the mandrel is adapted to rest on the surfaces ofspaced apart rollers or shafts 14 and 15. Preferably hardened steel wearplates 35 extend lengthwise on each face adjacent the base portions 19and 20. As may be appreciated, the mandrel may be used alternativelywith the common base portion 19 facing upwardly or the common baseportion 20 facing upwardly. The two pairs of wear surfaces permitposition of the mandrel in either of the two positions, with one of thetwo pairs of wear surfaces resting on the surfaces of shafts 14 and 15.

In use, the mandrel is initially placed within the band of material withmandrel support being provided by adjacent surfaces of shafts 14 and 15and with the wall of the tubular material passing between the mandreland the surfaces of the shafts. Feed or indexing means schematicallyrepresented by a pair of rollers 40 in FIG. 3 advances the band materialrelatively to the mandrel, the mandrel being positioned so that theupper corners of parts 23 are in contact with the inner surfaces of thecreases 12 and 13. As the band material is advanced, it is graduallyseparated by the opposed triangular faces. Variations in dimensions ofthe band cause a flexing of the biasing spring 24 and an automatic andcontinuous yielding of the parts 23. As the band moves past the lowermovable parts 23, creases 36 are imparted to the tape at positions whichare offset 90° from the initial creases. The tape is preferablythereafter drawn around the periphery of a roll 41 which reinforces theformation of the creases 35 and 36. As is recognized, the formation ofthese creases imparts stresses in the material which gives it a tendencyto naturally open which makes it possible to readily and rapidly fitcut-off pieces of the band of heat sealing material over the tops of thecontainers as best seen in FIG. 7.

The invention eliminates the tearing of the heat sealing material as itis advanced to the application station, allows for significant sizevariations in the material and substantially eliminates work stoppageswhich have heretofore arisen for this reason.

What is claimed is:
 1. A wedging mandrel for opening a tube of flexible,heat-shrinkable banding material or like tubular material wherein thetubular material is delivered in flat ribbon-like form with creased sideedges, said tube opening wedging mandrel comprising first and secondsets of planar wedge surface regions, the first and second sets ofplanar wedge surface regions converging towards and respectivelyterminating in first and second relatively narrow, elongated, wedgesurface portions, the first and second wedge surface portions beingdisposed at 90° to each other, means for supporting said mandrel withthe first of said wedge surface portions being positioned anddimensioned to receive and fit within the tube with the ends of saidfirst wedge surface portion adjacent the creased edges of the tube, feedmeans for advancing the tube relatively lengthwise of the mandrelwhereby the tube is wedged to the opened position, each of said firstand second elongated wedge surface portions having a grooved key wayextending lengthwise thereof, a pair of relatively moveable wedge-shapedparts mounted on each said first and second elongated surface portionand slidably moveable within the key way on said surface portion,biasing means for yieldably urging each said pair of parts to oppositeends of said elongated wedge surface portion on which said pair of partsis mounted, said parts each having a flat end surface and flatconverging wide wall surfaces, the flat converging side and end wallsurface of each of said parts being substantially coplanar with theplanar surface regions which terminate in and define the elongatedsurface portion on which the pair of parts is mounted, whereby the pairof parts on the first wedge surface portion resiliently bear against thecreased edges of the tube and the pair of parts on the second wedgesurface portion bear against the tube at positions disposed at 90° tothe creased edges of the tube.
 2. A wedging mandrel according to claim1, further including a thin plate member extending lengthwise from thevertex of each of said wedge-shaped parts, each said plate member havingan end surface sloping relatively inwardly from the base outer end ofthe part.
 3. Apparatus according to claim 2 further including parallelrelatively hard wear surfaces in the wedge surfaces of each set, andspaced apart supports interengageable with one of said set of wearsurfaces.